The present invention relates to a drive apparatus with recuperation capability for generating a rotational movement, in particular for a vehicle.
Drive apparatuses with recuperation capability for vehicles are known from the prior art.
Recuperative braking is being intensively pursued in road vehicle engineering with regard to possible energy and CO2 reductions. Even in the field of heavy utility vehicles, initial approaches are already being followed to utilize recuperative braking, in particular in special vehicles with a specific usage profile, such as for example refuse collection vehicles. Aside from the abovementioned saving with regard to fuel consumption and the associated CO2 reduction, the additional drive power from the utilization of the stored braking energy permits smaller dimensioning of the drive assemblies (downsizing), which yields further savings.
In many conventional truck-trailer combinations used for long-distance transport, the predominant part of the overall vehicle weight is borne by the trailer vehicle. Accordingly, the assignment of the number of axles of the tractor vehicle or of the semitrailer tractor to the axles of the trailer vehicle is very commonly 2:3, in particular if, as a trailer vehicle, use is made of a semitrailer and/or a trailer for example with a fifthwheel axle, on which the drawbar is also situated, and two non-steered (rear) axles.
In that case, the trailer vehicle has not only the greater number of axles but also, at said axles, offers far more favorable conditions for the installation of the assemblies required for recuperative braking than the tractor vehicle or the semitrailer tractor has at the drive axle or the steered axle.
This concept is picked up on in DE 10 2010 042 907 A1, in which it is provided that the system for recuperation of kinetic energy has a machine which is designed to convert at least a part of the kinetic energy of the trailer during a deceleration process of the trailer. An energy store is designed to receive the converted energy from the machine, to store said energy, and to release stored energy to the machine for conversion back into kinetic energy.
It is considered to be disadvantageous that, in the disclosed solution of DE 10 2010 042 907 A1, only the vehicle trailer is equipped with a recuperation system.
If the tractor vehicle or the semitrailer tractor has additional supporting axles (leading or trailing axles), these may however be equipped, in the same way as the trailer axles, with recuperative braking devices, because leading and trailing axles are of approximately the same construction as the trailer axles.
This concept is picked up on in DE 10 2006 046 419 A1, which describes an electric drive assembly for an axle of a vehicle. In the solution presented in DE 10 2006 046 419 A1, it is provided that the axle with the electric drive assembly is, according to DE 10 2006 046 419 A1, driven exclusively by means of said electric drive assembly. An electric machine can be connected by means of a transmission device and a differential gearing to the drive shafts of the axle. Thus, the electric machine—specified here as being of a conventional type of construction as a rotating-field or traveling-field machine—is arranged between the wheels of the axle or of the vehicle.
In DE 10 2006 046 419 A1, recuperation operation is also possible, for example by means of an energy store of the electric drive assembly.
However, in utility vehicles, which even nowadays still predominantly have rigid axles, said solution necessitates a modification of the axle system. Here, the axle tube diameter must be dimensioned to be large enough that a generator for both wheels, or in each case one generator per wheel, can be installed in the cavity of the axle tube. The drive is then correspondingly realized by means of drive shafts to the vehicle wheel. The transmission gearing may be arranged in the wheels or in the axle body. The axle may be dismountable for the purposes of allowing access to the electric machine, or, during the final assembly process, may be closed off by welding with the electric machine installed. Then, however, there is no possibility of the electric machine being exchanged.
As an alternative to the arrangement of an electric machine in the axle tube of the rigid axle of a utility vehicle, an arrangement as a wheel hub drive, for example via a gearing, is also conceivable.
DE 41 10 638 A1 describes an electric hub drive for tractor vehicles, wherein a wheel hub shaft, which is driven by a motor armature of an electric machine via a planetary gearing, bears a rotating part of a disk brake on that side of the motor housing which is situated opposite the wheel flange. A recuperation capability, or devices or means for that purpose, is/are not specified in DE 41 10 638 A1.
Here, however, the arrangement of the electric machine in a conventional type of construction as a rotating-field or traveling-field machine with correspondingly heavy coils for generating a rotating or traveling field in the region of the wheel is considered to be disadvantageous, because the hub drive according to DE 41 10 468 A1 greatly increases the unsprung masses of a tractor vehicle, and thus the driving dynamics characteristics and thus also the driving safety of the tractor vehicle can be adversely affected.
A direct drive of the wheel hub is alternatively also conceivable.
As an example of this, reference is made to DE 199 48 224 C1, which describes a vehicle with at least one wheel hub, which is mounted so as to be rotatable relative to the vehicle about a wheel axis, and with one or more wheels fastened to the wheel hub by means of a wheel rim. An electric machine which has a rotor arranged around a common machine axis and which has a stator, wherein the rotor is connected at least indirectly to the wheel hub and is a hollow body which is connected directly to the wheel rim and/or to the wheel hub, are specified.
By means of the design of the rotor as a hollow body, it is possible for a drive shaft of a conventional drive, for example of an internal combustion engine, to be led through the passage of the rotor, such that the electric machine can be activated or deactivated at any time, because the electric machine exerts a torque directly, that is to say without an additional hub drive shaft etc., on the wheel to be driven. A recuperation capability, or devices or means for that purpose, are not described in DE 199 48 224 C1.
Here, it is also considered to be disadvantageous that the electric machine, in this case in a conventional type of construction as a rotating-field or traveling-field machine, by means of correspondingly heavy coils for generating a rotating or traveling field in the region of the wheel, greatly increases the unsprung masses of a tractor vehicle, and thereby adversely affects the driving dynamics characteristics and thus also the driving safety of the tractor vehicle.
A concept of a drive apparatus with recuperation capability suitable for use in such road-going vehicles could furthermore be configured such that the axles of the trailer vehicle impart the predominant fraction of the recuperative braking work and the recovered (electrical) energy is stored in the trailer vehicle.
It is furthermore conceivable for the tractor vehicle to be equipped with an electric machine rather than a retarder, ideally at the drive location of the latter, which electric machine likewise imparts recuperative braking work and can also output corresponding drive power. Here, it is assumed that the entire permanent-braking power of the recuperative devices of tractor vehicle and trailer vehicle render the retarder superfluous. The omission of the retarder and of its required heat exchanger device can on its own greatly compensate the additional costs for the recuperative braking system.
With regard to the drive in the trailer vehicle, legal regulations must be observed. To ensure driving stability, suitable coupling force regulation is required, by means of which it is ensured that the trailer does not under any circumstances run up onto the tractor vehicle or onto the semitrailer tractor, that is to say the tractor vehicle or the semitrailer tractor still imparts a minimum traction force under all circumstances.
This concept is likewise picked up on in DE 10 2010 042 907 A1.
The controller of the recuperation system according to DE 10 2010 042 907 A1 is designed to control the machine such that the machine converts kinetic energy for being received by the energy store to a degree which correlates with the extent to which the thrust force of the trailer vehicle effects a compression of an overrunning brake coupling. The degree of energy conversion may in this case be proportional to the force.
In particular, the recuperation may be implemented to an extent which is set to be proportional to the braking action of an additional service brake, such as for example a retarder.
It is however considered to be disadvantageous that, according to the solution of DE 10 2010 042 907 A1, only the vehicle trailer is equipped with a recuperation system.
It is also conceivable that the controller of a drive apparatus with recuperation capability, in interaction with an energy store for vehicles, operates, as it were, with predictive energy management in a manner dependent on the route to be traveled, such that, at all times, sufficient recuperative energy is available for the respective route in order to generate a maximum energy saving for a conventional drive of the vehicle from the route covered.
This concept is picked up on in DE 10 2011 118 543 A1. A state of charge of an energy store resulting from control or regulation of the drive apparatus with recuperation capability is predictively controlled or regulated in a manner dependent on an upcoming route, on the predicted recoverable electrical energy on said route, and/or on a predicted energy requirement for a secondary drive function.
It is however considered to be disadvantageous that the predictive control or regulation is provided only for a “conventional” hybrid drivetrain, that is to say for an internal combustion engine which is coupled directly or via a gearing to an electric machine. DE 10 2011 118 543 A1 gives no details regarding the specific design of the electric machine and regarding the use of a drive apparatus with recuperation capability at trailer axles or at axles on the vehicle which are not driven by an internal combustion engine.
Furthermore, it is conceivable that, by means of such a drive apparatus with recuperation capability for vehicles, the trailer vehicle is provided with a dedicated drive, such that the trailer vehicle can be moved or maneuvered even without a tractor vehicle or semitrailer tractor. Owing to the mobile flexibility thus obtained, this yields further functions for the trailer vehicle, for example as a locally flexible or mobile store for just-in-time deliveries with multiple drop-off points at a production hall, or for the parking of the trailer vehicle on ferries, or for loading the trailer vehicle on railway carriages, or for maneuvering or launching on loading ramps.
DE 10 2008 001 565 A1 describes a trailer with at least one axle and with a fifthwheel coupling for receiving a semitrailer. Such a trailer is referred to in technical terminology as a “dolly”.
For better maneuverability of a coupled-on semitrailer, it is provided that the dolly has an electric machine comprising an energy store as drive means. A recuperation capability, or devices or means for that purpose, are not described in DE 10 2008 001 565 A1. Here, it is considered to be disadvantageous that a semitrailer can be maneuvered without a tractor only in conjunction with a dolly. A dolly has however hitherto been used significantly only in conjunction with a so-called EuroCombi truck-trailer combination, wherein a EuroCombi truck-trailer combination of said type with a dolly is constructed from a three-axle tractor vehicle, the dolly and a conventional semitrailer. Such a truck-trailer combination exceeds the previously maximum admissible length of tractor-trailer combinations in almost all European countries, such that EuroCombi truck-trailer combinations of said type have hitherto been licensed for road transport only in Scandinavia, wherein in Germany, for example, they are presently only allowed to drive under test conditions on selected routes with special authorization and with a reduced admissible total weight of 40 tonnes.
The invention therefore has the object of eliminating or substantially reducing the above-described disadvantages.
It is a further object to provide an improved tractor vehicle or an improved semitrailer tractor.
Yet further objects consist in specifying a trailer vehicle and an improved truck-trailer combination.
The present invention achieves said object by means of a drive apparatus, a tractor vehicle or a semitrailer tractor, a trailer vehicle, and a truck-trailer combination, in accordance with embodiments of the invention.
Accordingly, it is provided according to the invention that the drive apparatus is in the form of a hub direct drive and has an electric machine which operates in accordance with the piezoelectric operating principle.
A tractor vehicle according to the invention or a semitrailer tractor is designed such that the wheels of the leading axle and/or the wheels of the trailing axle have the drive apparatus according to the invention.
A trailer vehicle according to the invention is equipped such that the wheels of the trailer vehicle axles of the trailer vehicle have the drive apparatus according to the invention.
A truck-trailer combination according to the invention is composed of the tractor vehicle according to the invention or the semitrailer tractor according to the invention and at least one trailer vehicle according to the invention.
The invention yields an increased overall drive power of a truck-trailer combination, which is an advantageous effect in particular on routes with ascending gradients and when increased acceleration is required. Furthermore, driving with purely electric drive is also advantageously possible by means of the drive apparatus, for example in order to permit travel in environmental zones in city centers.
The drive apparatus according to the invention also has an advantageous effect owing to the improved traction of a truck-trailer combination in the case of which the wheels of the axles of the at least one trailer vehicle and/or the leading axle and/or the trailing axle of the tractor vehicle and/or of the semitrailer tractor are each equipped with a drive apparatus. In this way, a launch aid can be realized, which has an advantageous effect, in particular in winter, with regard to the availability and the driving safety of a truck-trailer combination of said type.
Furthermore, by means of the drive apparatus according to the invention, it is advantageously possible to realize a maneuvering facility of the trailer without a tractor vehicle. In the case of a semitrailer, this is possible in particular by means of a supporting winch which has wheels on its free end. As a result of the wheels of the trailer axles being equipped with the drive apparatus, the trailer or semitrailer is made automotive, and can thus, with corresponding remote control, be moved up to loading ramps without a tractor vehicle.
Furthermore, recuperative braking can be realized by means of the drive apparatus according to the invention. Here, the toothing of the swash plate is in engagement by means of a disconnect switching function.
In conjunction with an electrical energy store which is arranged in the trailer vehicle and/or in the tractor vehicle and/or in the semitrailer tractor, the kinetic energy of the vehicle or of the truck-trailer combination can, via the wheels during braking processes and during overrun operation of the truck-trailer combination, be advantageously recovered and stored by means of the drive apparatus according to the invention.
Such a function also has an advantageous effect as a result of the increase of the overall braking power of the truck-trailer combination. Furthermore, by means of the drive apparatus, an advantageous, wear-free permanent brake is provided, which under some circumstances renders a retarder superfluous.
Furthermore, it is advantageously possible by means of such a function to prevent the trailer vehicle from running up onto the tractor vehicle or onto the semitrailer tractor.
Likewise, with the drive apparatus according to the invention, it is possible to realize a wheel-selective drive intervention or deceleration intervention. Here, the toothing of the swash plate of the drive apparatus(es) is in engagement by means of the disconnect switching function, by means of which the wheel-selective drive intervention or deceleration intervention can be realized.
Such a function advantageously yields expanded possibilities for driving stability regulation for the entire truck-trailer combination, for example for an electronic stability program (ESP) which also takes the trailer vehicle operation into consideration.
Furthermore, possibilities arise for decreasing the turning circle of the truck-trailer combination, which has an advantageous effect when traveling around rotary intersections, in particular if, as a result of partial loading or unloading of the truck-trailer combination, the center of gravity of the overall vehicle has been shifted and, accordingly, even traveling around a rotary intersection with the so-called BOKraft [German regulation on the operation of motor carriers in passenger transport] circle dimensions is associated with difficulties.
Finally, with the drive apparatus according to the invention, the swash plate can be moved out of engagement by means of the disconnect switching function, and thus a freewheel function of the drive apparatus can be realized. In this way, during relatively long phases without significant braking interventions, or without situations in which additional drive energy is required or can be advantageously used, the drive apparatus can be protected against excessive wear. Such driving states arise for example on freeway journeys on routes without steep ascending or descending gradients.
Here, it is advantageous that, by means of such a function, an additional driving resistance that would be caused by the engaged toothing of the swash plate is eliminated.
The actuators are advantageously supported on a base of an actuator housing. The swash plate preferably has a bevel-gear-like geometry and is equipped with a toothing. The effective diameter of the actuators, which act directly on the swash plate, is advantageously selected so as to be smaller than the pitch circle diameter of the swash plate toothing by a factor of up to 5, preferably by a factor of 2.5 to 3.5.
In a further advantageous design variant of the drive apparatus, the toothing of the swash plate or the toothing of the drive disk is designed such that the toothing of the drive disk has one tooth fewer than the toothing of the swash plate. This yields a significant reduction ratio.
The toothing stroke of the swash plate is advantageously selected such that the toothing stroke results in a difference in circumferential magnitude between the deflected swash plate and the swash plate in a rest position which corresponds to one tooth pitch.
In one embodiment, the at least three actuators have in each case one housing. In this way, a simple construction and simultaneous protection of the actuators are possible.
It is provided that the housing has slots in a radial circumferential direction. In this way, the housing can firstly be more lightweight and can secondly be more elastic. Furthermore, an actuator is advantageously elastically preloaded by the housing.
In one embodiment, the drive apparatus has two groups of actuators with in each case at least three actuators. Here, it is provided that the actuators of the first group have an opposite direction of action to the second group of actuators. In this way, the available structural space in a wheel hub can be advantageously utilized.
It is furthermore provided that the at least three actuators of the first group are arranged with a 120° pitch, and the actuators of the second group, which are likewise arranged with a 120° pitch, are offset by 60° in relation to the actuators of the first group. This yields as uniform a distribution as possible for the introduction of force.
For a further embodiment, it is advantageous that the two groups of actuators with in each case at least three actuators are inserted in an actuator housing, because this yields a compact construction.
Furthermore, in a further embodiment, the actuator housing has means for heat dissipation, such as for example cooling fins, on its outer wall. An effective dissipation of heat is thus possible at the source.
The actuator housing surrounds the actuators radially in each case in the manner of a housing and axially at in each case one end of the actuators. Such a construction facilitates the assembly thereof.
In a further embodiment, the actuator housing is extended through by a supporting column. Furthermore, the supporting column is extended through by a central bolt. This yields a compact construction.
For a further embodiment, the central bolt has a head part. This also contributes to a compact and simple assembly.
The central bolt has a shank, a threaded section and a passage bore. In this way, it is possible for the actuator-force-conducting components to be able to be subjected to a preload by means of the central bolt. This is advantageous because the preload can, by means of the construction, be imparted centrally.
The supporting column may be produced from a technical ceramic material. For example, the supporting column is produced from silicon carbide. This yields a particularly robust and rigid design.
The central bolt may be produced from a tempering steel of quality 10.9 or 12.9. Small tolerances can thus be achieved.
It is likewise advantageous if the actuator housing is produced from a material with low density and high modulus of elasticity. It is thus possible for the actuator housing to be produced for example from a technical ceramic material. The actuator housing may preferably also be produced from silicon carbide (SiC).
In one embodiment, the actuators of the first group act directly, and the actuators of the second group act indirectly, on the swash plate. The action may be periodic. It is also possible for the actuators to act periodically on the swash plate in accordance with a sinusoidal function which is phase-offset by 120°.
In a further embodiment, the actuators of the second group act directly, and the actuators of the first group act indirectly, on the head part of the central bolt. This action may also be periodic, or may occur periodically in accordance with a sinusoidal function which is phase-offset by 120°.
In a yet further embodiment, it is provided that the actuators of the second group are actuated, in relation to the phase position of the actuation of the actuators of the first group, so as to yield a maximum overlap of the strokes of the actuators. It is also possible for the actuators of the second group to be actuated, in relation to the phase position of the actuation of the actuators of the first group, so as to yield a maximum action of force of the actuators on the swash plate. In this way, an effective action of the actuators on the swash plate and for the drive is made possible.
The swash plate may have a spur toothing. Other types of toothing are self-evidently also possible.
In another embodiment, the swash plate is formed as a composite component. Here, the swash plate may have a swash plate body which is produced from glass-fiber-reinforced plastic (GRP). It is thus possible to achieve a high strength with simultaneously low weight.
In a yet further embodiment, the toothing of the swash plate and the toothing of the drive disk may preferably have a modulus of 0.25 to 0.7; particularly preferably a modulus of 0.35 to 0.5. An efficient transmission of power and motion is thus possible.
In a further embodiment, the drive apparatus has an anchor plate. The anchor plate may be equipped with a spur toothing. The spur toothing of the swash plate geometrically corresponds to the spur toothing of the anchor plate. The anchor plate can thus form a fixed base for the swash plate, wherein the toothings which are in engagement permit, in a simple manner, a certain degree of relative mobility of the swash plates relative to the fixed anchor plate.
In a yet further embodiment, the drive apparatus has a pivot bearing between the swash plate and the drive disk. Here, it is advantageous if the pivot bearing involves rolling contact. Friction is reduced in this way.
In a yet further embodiment, the rolling contact is formed by a component with a spherical-sector-shaped geometry, which is inserted into a stepped bore of the swash plate, and a spherical-sector-shaped depression of the drive disk, between which there is arranged a bearing cage in which rolling bearing balls are held. This yields a compact construction.
In one embodiment, a transmission of a torque between the drive disk and a wheel hub is realized by means of a freewheel-like roller-ramp system. In this way, a freewheel is formed which two functions, specifically drive of the wheel hub by means of the drive disk and drive of the drive disk by means of the wheel hub, for example during recuperation operation.
Furthermore, a part of the wheel hub which accommodates the drive apparatus is covered toward the outside by a protective cap. The protective cap is connected to a wheel hub housing. This yields a space-saving construction, which simultaneously ensures cooling of the drive apparatus, because the protective cap is situated with the latter in the lateral relative wind of the vehicle.
In a yet further embodiment, it is provided that the drive apparatus has a spring element between the base of the stepped bore of the swash plate and the component with spherical-sector-shaped geometry. The spring element may for example be a plate spring, which yields a space-saving construction.
In one embodiment, the plate spring is supported on the base of the stepped bore of the swash plate and acts with its spring force against the component with spherical-sector-shaped geometry. In this way, distinct states in different operating states of the drive apparatus are made possible.
Here, the drive apparatus may have a ring between the component with spherical-sector-shaped geometry and the plate spring.
If the protective cap has openings, a simple forced air flow for cooling the drive apparatus when the vehicle is in motion is possible.
For an advantageously simple seal, the drive apparatus may, in one variant, have a seal which surrounds the head part and which is fastened to the actuator housing.
It is also possible for the drive apparatus to have a disk-shaped seal which seals off the actuator housing on its side facing toward the swash plate, and a swash plate gearing formed from the swash plate and the drive disk, and bearing points, with respect to the surroundings.
The disk-shaped seal has, on its wheel-hub-side circumference, a seal bead by means of which the seal is fixed between the wheel hub and the protective cap. Furthermore, the disk-shaped seal may have, on its actuator-housing-side circumference, a seal bead by means of which the seal is fixed between the actuator housing and the swash plate. In this way, simple installation is possible.
In another embodiment, the functions of drive, recuperative braking and freewheeling of the drive apparatus are realized by means of the disconnect switching function. For this purpose, the drive apparatus may have a stepped switching function. The stepped switching function acts on the swash plate gearing, wherein the swash plate gearing is formed from a swash plate and a drive disk, and realizes at least two transmission ratio stages of the swash plate gearing. In this way, the drive apparatus can advantageously have three functions.
The tractor vehicle and/or the semitrailer tractor may have an energy store in which energy obtained by means of the recuperative braking by means of the drive apparatus is stored and from which stored energy is released for drive of the tractor vehicle or of the semitrailer tractor by means of the drive apparatus. Said store may for example be a vehicle battery and/or an additional battery/accumulator. It is self-evidently also possible for the trailer vehicle to have an energy store in which the energy obtained by means of the drive apparatus as a result of the recuperative braking is stored and from which stored energy is released for drive of the trailer vehicle by means of the drive apparatus.
Further advantageous embodiments of the invention will emerge from the subclaims.